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  • 1
    Online Resource
    Online Resource
    Wiley ; 2016
    In:  Environmental Microbiology Vol. 18, No. 2 ( 2016-02), p. 514-524
    In: Environmental Microbiology, Wiley, Vol. 18, No. 2 ( 2016-02), p. 514-524
    Abstract: C rocosphaera watsonii is a unicellular nitrogen ( N 2 )‐fixing cyanobacterium with ecological importance in oligotrophic oceans. In cultivated strains there are two phenotypes of C . watsonii (large and small cells) with differences that could differentially impact biogeochemical processes. Recent work has shown the phenotypes diverged through loss or addition of type‐specific genes in a fraction of their genomes, whereas the rest of the genomes were maintained at 99–100% DNA identity. Previous molecular assays for C . watsonii abundances targeted the conserved regions and therefore could not differentiate between phenotypes, so their relative distributions in natural communities were unknown. To determine phenotype distributions, this study developed and applied type‐specific quantitative polymerase chain reaction assays to samples from the N orth and S outh P acific. Abundances of both C rocosphaera types declined sharply with depth between 45 and 75 m in both sites. In surface water small cells were 10–100 times more abundant than large cells in the N . P acific, whereas in the S . P acific the two phenotypes were nearly equal. Evidence for large cell aggregation was only found in N . P acific samples. The differences in C . watsonii sub‐populations in the N orth and S outh P acific have direct implications for biogeochemistry and carbon export in oligotrophic gyres.
    Type of Medium: Online Resource
    ISSN: 1462-2912 , 1462-2920
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2016
    detail.hit.zdb_id: 2020213-1
    SSG: 12
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  • 2
    In: Limnology and Oceanography, Wiley, Vol. 63, No. S1 ( 2018-03)
    Abstract: The marine picocyanobacteria Prochlorococcus and Synechococcus dominate primary production in oligotrophic oceans, but their role in the particulate organic carbon (POC) flux into the deeper ocean remains unresolved. Here, we present for the first‐time data on the absolute clade and strain‐specific contribution to POC flux of two of the most abundant clades of Synechococcus (II and III) and strains of Prochlorococcus (high‐light strain MIT 9312 and low‐light strain MIT 9313) in the Sargasso Sea, by targeting the 23S‐16S rDNA internally transcribed spacer region using quantitative Polymerase Chain Reaction. We collected seawater samples and sinking particles using shallow sediment traps during winter and summer 2012 around the Bermuda Atlantic Time Series station. Both clades of Synechococcus had a higher contribution to the total POC flux during winter compared to the summer, with both clades contributing up to 2.7% to the total winter POC flux. Prochlorococcus was more abundant during the summer, but both strains of Prochlorococcus contributed less than 0.2% to the POC flux in both seasons. We found these differences in the contribution to flux to be mainly due to the smaller size of the Prochlorococcus . In addition, the flux of Synechococcus clade III, and Prochlorococcus MIT9312 was enhanced relative to their standing stock in a cyclonic eddy sampled during winter 2012. Using quantification of genetic markers, this study establishes distinct clade‐and strain specific patterns in POC flux among the most abundant picophytoplankton groups in the Atlantic Ocean.
    Type of Medium: Online Resource
    ISSN: 0024-3590 , 1939-5590
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2018
    detail.hit.zdb_id: 2033191-5
    detail.hit.zdb_id: 412737-7
    SSG: 12
    SSG: 14
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  • 3
    In: Environmental Microbiology, Wiley, Vol. 10, No. 3 ( 2008-03), p. 727-737
    Abstract: The facultative symbiont of Riftia pachyptila , named here Candidatus Endoriftia persephone , has evaded culture to date, but much has been learned regarding this symbiosis over the past three decades since its discovery. The symbiont population metagenome was sequenced in order to gain insight into its physiology. The population genome indicates that the symbionts use a partial Calvin–Benson Cycle for carbon fixation and the reverse TCA cycle (an alternative pathway for carbon fixation) that contains an unusual ATP citrate lyase. The presence of all genes necessary for heterotrophic metabolism, a phosphotransferase system, and dicarboxylate and ABC transporters indicate that the symbiont can live mixotrophically. The metagenome has a large suite of signal transduction, defence (both biological and environmental) and chemotaxis mechanisms. The physiology of Candidatus Endoriftia persephone is explored with respect to functionality while associated with a eukaryotic host, versus free‐living in the hydrothermal environment.
    Type of Medium: Online Resource
    ISSN: 1462-2912 , 1462-2920
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2008
    detail.hit.zdb_id: 2020213-1
    SSG: 12
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  • 4
    Online Resource
    Online Resource
    Wiley ; 2013
    In:  Environmental Microbiology Reports Vol. 5, No. 5 ( 2013-10), p. 697-704
    In: Environmental Microbiology Reports, Wiley, Vol. 5, No. 5 ( 2013-10), p. 697-704
    Abstract: The production of hydrogen ( H 2 ) is an inherent component of biological dinitrogen ( N 2 ) fixation, and there have been several studies quantifying H 2 production relative to N 2 fixation in cultures of diazotrophs. However, conducting the relevant measurements for a field population is more complex as shown by this study of N 2 fixation, H 2 consumption and dissolved H 2 concentrations in the oligotrophic N orth P acific O cean. Measurements of H 2 oxidation revealed microbial consumption of H 2 was equivalent to 1–7% of ethylene produced during the acetylene reduction assay and 11–63% of 15 N 2 assimilation on a molar scale. Varying abundances of C rocosphaera and T richodesmium as revealed by nif H gene abundances broadly corresponded with diel changes observed in both N 2 fixation and H 2 oxidation. However, no corresponding changes were observed in the dissolved H 2 concentrations which remained consistently supersaturated (147–560%) relative to atmospheric equilibrium. The results from this field study allow the efficiency of H 2 cycling by natural populations of diazotrophs to be compared to cultured representatives. The findings indicate that dissolved H 2 concentrations may depend not only on the community composition of diazotrophs but also upon relevant environmental parameters such as light intensity or the presence of other H 2 ‐metabolizing microorganisms.
    Type of Medium: Online Resource
    ISSN: 1758-2229 , 1758-2229
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2013
    detail.hit.zdb_id: 2485218-1
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  • 5
    In: Environmental Microbiology Reports, Wiley, Vol. 5, No. 5 ( 2013-10), p. 705-715
    Abstract: In contrast to cyanobacteria, the significance of bacteria and archaea in oceanic N 2 fixation remains unknown, apart from the knowledge that their nitrogenase ( nifH ) genes are diverse, present in all oceans and at least occasionally expressed. Non‐cyanobacterial nifH sequences often occur as contamination from reagents and other sources, complicating the detection and interpretation of environmental phylotypes. We amplified and sequenced partial nifH gene fragments directly from cell populations sorted by fluorescence activated cell sorting from water collected in the N orth P acific S ubtropical G yre ( NPSG ). Sequences recovered (195 total) included presumed heterotrophic or photoheterotrophic non‐cyanobacterial nifH phylotypes previously unreported in the NPSG . A nifH sequence previously found in the S outh P acific G yre ( HM 210397) was exclusively recovered from sorted picoeukaryote populations, and was detected in water column samples using quantitative PCR (q PCR ), with 60% of samples detected in the 〉  10 μm size fraction in addition to the 0.2–10 μm size fraction. A novel cluster 3‐like nifH sequence was also recovered from discrete cell sorts and detected by q PCR in environmental samples. This approach enables the detection of rare nifH phylotypes, identifies possible associations with larger cells or particles and offers a possible solution for distinguishing reagent contaminants from real microbial community components.
    Type of Medium: Online Resource
    ISSN: 1758-2229 , 1758-2229
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2013
    detail.hit.zdb_id: 2485218-1
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  • 6
    Online Resource
    Online Resource
    Wiley ; 2014
    In:  Environmental Microbiology Reports Vol. 6, No. 1 ( 2014-02), p. 122-122
    In: Environmental Microbiology Reports, Wiley, Vol. 6, No. 1 ( 2014-02), p. 122-122
    Type of Medium: Online Resource
    ISSN: 1758-2229 , 1758-2229
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2014
    detail.hit.zdb_id: 2485218-1
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  • 7
    In: Limnology and Oceanography, Wiley, Vol. 66, No. 6 ( 2021-06), p. 2159-2173
    Abstract: Often considered detrimental to the environment and human activities, jellyfish blooms are increasing in several coastal regions worldwide. Yet, the overall effect of these outbreaks on ecosystem productivity and structure are not fully understood. Here we provide evidence for a so far unanticipated role of jellyfish in marine nitrogen cycling. Pelagic jellyfish release nitrogen as a metabolic waste product in form of ammonium. Yet, we observed high rates of nitrification (NH 4 +  → NO 3 − , 5.7–40.8 nM gWW −1 [wet weight] h −1 ) associated with the scyphomedusae Aurelia aurita , Chrysaora hysoscella , and Chrysaora pacifica and low rates of incomplete nitrification (NH 4 +  → NO 2 − , 1.0–2.8 nM gWW −1  h −1 ) associated with Chrysaora fulgida , C . hysoscella , and C . pacifica . These observations indicate that microbes living in association with these jellyfish thrive by oxidizing the readily available ammonia to nitrite and nitrate. The four studied species have a large geographic distribution and exhibit frequent population outbreaks. We show that, during such outbreaks, jellyfish‐associated release of nitrogen can provide more than 100% of the nitrogen required for primary production. These findings reveal a so far overlooked pathway when assessing pelagic nitrification rates that might be of particular relevance in nitrogen depleted surface waters and at high jellyfish population densities.
    Type of Medium: Online Resource
    ISSN: 0024-3590 , 1939-5590
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2021
    detail.hit.zdb_id: 2033191-5
    detail.hit.zdb_id: 412737-7
    SSG: 12
    SSG: 14
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